Emma Grayling was a human empathic psychic in the 20th century. She described herself as Major Alec Palmer's "assistant". Alec used the psychic abilities of Emma to capture images of the Caliburn Ghast in Alec's house, Caliburn House.
On the fourth day of ghost hunting, 25 November 1974, the Eleventh Doctor arrived with Clara Oswald. Under the guise of a member of the ministry, he joined in with the ghost hunting. With Alec's help, the Doctor discovered the ghost was the time traveller, Hila Tacorien, trapped in a pocket universe.
With the help of Emma's psychic powers creating a wormhole, Hila was pulled out of the collapsing pocket universe, but she was unable to keep the connection and the Doctor was left behind. Alec convinced Emma to reopen the wormhole, and Clara rescued the Doctor in the TARDIS.
Emma confronted the Doctor as to his true motive in coming to see them, discerning that he had come for her. He acknowledged this and said he wanted to ask her about Clara's nature. She responded that she was a normal girl.
The Doctor told Alec and Emma that Emma's psychic connection to Hila was so strong because Hila was their descendant, and what Alec and Emma needed to was to "hold hands" and to "keep doing that, and never let go". As a final favour, Emma reopened the wormhole one last time, so that the Doctor and Clara could rescue the creature, which had been stalking Hila, from the pocket universe, and reunite him with his mate in Caliburn House. (TV: Hide)